Clean up callable type mismatch errors
```rust
error[E0593]: closure takes 1 argument but 2 arguments are required here
--> ../../src/test/ui/mismatched_types/closure-arg-count.rs:13:15
|
13 | [1, 2, 3].sort_by(|(tuple, tuple2)| panic!());
| ^^^^^^^ -------------------------- takes 1 argument
| |
| expected closure that takes 2 arguments
```
instead of
```rust
error[E0281]: type mismatch: the type `[closure@../../src/test/ui/mismatched_types/closure-arg-count.rs:13:23: 13:49]` implements the trait `for<'r> std::ops::FnMut<(&'r {integer},)>`, but the trait `for<'r, 'r> std::ops::FnMut<(&'r {integer}, &'r {integer})>` is required (expected a tuple with 2 elements, found one with 1 elements)
--> ../../src/test/ui/mismatched_types/closure-arg-count.rs:13:15
|
13 | [1, 2, 3].sort_by(|(tuple, tuple2)| panic!());
| ^^^^^^^
```
Fix#21857, re #24680.
Add a way to get shorter spans until `char` for pointing at defs
```rust
error[E0072]: recursive type `X` has infinite size
--> file.rs:10:1
|
10 | struct X {
| ^^^^^^^^ recursive type has infinite size
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `X` representable
```
vs
```rust
error[E0072]: recursive type `X` has infinite size
--> file.rs:10:1
|
10 | struct X {
| _^ starting here...
11 | | x: X,
12 | | }
| |_^ ...ending here: recursive type has infinite size
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `X` representable
```
Re: #35965, #38246. Follow up to #38328.
r? @jonathandturner
```rust
error[E0072]: recursive type `X` has infinite size
--> file.rs:10:1
|
10 | struct X {
| ^^^^^^^^ recursive type has infinite size
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `X` representable
```
vs
```rust
error[E0072]: recursive type `X` has infinite size
--> file.rs:10:1
|
10 | struct X {
| _^ starting here...
11 | | x: X,
12 | | }
| |_^ ...ending here: recursive type has infinite size
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `X` representable
```
When we are generalizing a super/sub-type, we have to replace type
variables with a fresh variable (and not just region variables). So if
we know that `Box<?T> <: ?U`, for example, we instantiate `?U` with
`Box<?V>` and then relate `Box<?T>` to `Box<?V>` (and hence require that
`?T <: ?V`).
This change has some complex interactions, however:
First, the occurs check must be updated to detect constraints like `?T
<: ?U` and `?U <: Box<?T>`. If we're not careful, we'll create a
never-ending sequence of new variables. To address this, we add a second
unification set into `type_variables` that tracks type variables related
through **either** equality **or** subtyping, and use that during the
occurs-check.
Second, the "fudge regions if ok" code was expecting no new type
variables to be created. It must be updated to create new type variables
outside of the probe. This is relatively straight-forward under the new
scheme, since type variables are now independent from one another, and
any relations are moderated by pending subtype obliations and so forth.
This part would be tricky to backport though.
cc #18653
cc #40951
When trying to do a binary operation with missing implementation, for
example `1 + Some(2)`, provide an explicit help message:
```
note: no implementation for `{integer} + std::option::Option<{integer}>`
```
Use `rustc_on_unimplemented` for the suggestions. Move cfail test to ui.
Provide the following output:
```
error[E0277]: the trait bound `Bar: Foo<usize>` is not satisfied
--> $DIR/issue-21659-show-relevant-trait-impls-2.rs:38:8
|
38 | f1.foo(1usize);
| ^^^ the trait `Foo<usize>` is not implemented for `Bar`
|
= help: the following implementations were found:
<Bar as Foo<i8>>
<Bar as Foo<i16>>
<Bar as Foo<i32>>
<Bar as Foo<u8>>
and 2 others
error: aborting due to previous error
```
instead of
```
error[E0277]: the trait bound `Bar: Foo<usize>` is not satisfied
--> $DIR/issue-21659-show-relevant-trait-impls-2.rs:38:8
|
38 | f1.foo(1usize);
| ^^^ the trait `Foo<usize>` is not implemented for `Bar`
|
= help: the following implementations were found:
= help: <Bar as Foo<i8>>
= help: <Bar as Foo<i16>>
= help: <Bar as Foo<i32>>
= help: <Bar as Foo<u8>>
= help: and 2 others
error: aborting due to previous error
```
Point out the known type when field doesn't satisfy bound
For file
```rust
use std::path::Path;
fn f(p: Path) { }
```
provide the following error
```nocode
error[E0277]: the trait bound `[u8]: std::marker::Sized` is not satisfied in `std::path::Path`
--> file.rs:3:6
|
3 | fn f(p: Path) { }
| ^ within `std::path::Path`, the trait `std::marker::Sized` is not implemented for `[u8]`
|
= note: `[u8]` does not have a constant size known at compile-time
= note: required because it appears within the type `std::path::Path`
= note: all local variables must have a statically known size
```
Fix#23286.
For file
```rust
use std::path::Path;
fn f(p: Path) { }
```
provide the following error
```nocode
error[E0277]: the trait bound `[u8]: std::marker::Sized` is not satisfied in `std::path::Path`
--> file.rs:3:6
|
3 | fn f(p: Path) { }
| ^ within `std::path::Path`, the trait `std::marker::Sized` is not implemented for `[u8]`
|
= note: `[u8]` does not have a constant size known at compile-time
= note: required because it appears within the type `std::path::Path`
= note: all local variables must have a statically known size
```
[9/n] rustc: move type information out of AdtDef and TraitDef.
_This is part of a series ([prev](https://github.com/rust-lang/rust/pull/37688) | [next]()) of patches designed to rework rustc into an out-of-order on-demand pipeline model for both better feature support (e.g. [MIR-based](https://github.com/solson/miri) early constant evaluation) and incremental execution of compiler passes (e.g. type-checking), with beneficial consequences to IDE support as well.
If any motivation is unclear, please ask for additional PR description clarifications or code comments._
<hr>
Both `AdtDef` and `TraitDef` contained type information (field types, generics and predicates) which was required to create them, preventing their use before that type information exists, or in the case of field types, *mutation* was required, leading to a variance-magicking implementation of `ivar`s.
This PR takes that information out and the resulting cleaner setup could even eventually end up merged with HIR, because, just like `AssociatedItem` before it, there's no dependency on types anymore.
(With one exception, variant discriminants should probably be moved into their own map later.)
In general having all these different structs for "origins" is not
great, since equating types can cause obligations and vice-versa. I
think we should gradually collapse these things. We almost certainly
also need to invest a big more energy into the `error_reporting` code to
rationalize it: this PR does kind of the minimal effort in that
direction.
